I downloaded AirDroid this evening on my HTC Eris Android 2.1, and was attempting to use it to transfer nearly 2,500 photos to my PC. Rather than move everything at once, I would download about 100 photos at a time, save them on my computer, delete them from the phone, and go on to the next batch.

During one of these "deletes," ALL of my photos were somehow deleted from the phone, including the over 2,000 that I hadn't yet been able to transfer to my PC. I have no idea how or why this happened, but it seemed to coincide with the online browser becoming unresponsive - seems to have been some kind of glitch. The SD card has suddenly gone from showing 3.9/7 GB full to showing
116.5 MB full - those photos were pretty much all I had on the phone.

How can I recover these photos? Some of them are quite important to me...

I had the same thing happen using airdroid,and gave Pandora Recovery ( free) a shot. I was skeptical, but it was a last ditch effort. It worked- I managed to recover everything! So i'd give it a try since no one else has responded to your post. Good luck, radioflyer!
Deeyan

Whatever you do, do not write anything else to your SD card until you have recovered your photos or you may be writing over the top of where your photos are. You might even be best getting the SD card into a PC then using software installed on the PC's own hard-drive to be sure nothing on your phone is writing to it behind the scenes.

CardRecovery is the leading photo recovery software for memory card used by digital
camera or phone. It can effectively recover lost, deleted, corrupted or
formatted photos and video files from various memory cards. It supports
almost all memory card types including SD Card, MicroSD, SDHC, CF
(Compact Flash) Card, xD Picture Card, Memory Stick and more.

The modern age is epitomised by our daily consumption and creation of digital content. If that includes photos, videos and software, then the question of storage arises - to keep the stuff you want to save.
An example of such a painful situation, is the loss of photos from the now-ubiquitous form of flash storage - the SD card, which we all use on our cameras or mobile phones (in the smaller microSD card form).
I will suggest 3 free software to recover deleted file:
1.Recuva (version 1.51.1063)
2.Pandora Recovery (version 2.1.1)
3.Stellar Phoenix Mac Photo Recovery (for OS X)

Recuva (version 1.51.1063) is a 4.02MB free download, and works with PCs running Windows 2000 or above. To recover your files from your SD card, load the card on the PC via a card reader, select the corresponding drive in Recuva's drop down menu. Run a scan via the Scan button.

Pandora Recovery (for Windows) - Pandora Recovery (version 2.1.1) is a free-to-use tool that is a 3.12MB download. It supports PCs running Windows XP or above. Just like with Recuva, users will need to load their SD card via a card reader, and perform either a Quick Scan or Deep (Surface) Scan to throw up results of deleted and corrupted files. The second option is for formatted memory, and while it is slower, it should turn up more results than a quick scan.

The SD card is important part of the phone. The physical damage of card recovery is more complicated than logical. If physical damage is there, then get the help of professional service personnel. The other logical part can be corrected or restore the image or video using many SD card recovery tool. To check the damage of the card run chkdsk command to find the bad sector. The SD Formatter, Disk Heal, Recuva, PhotoRec are the few names of SD card recovery. At first scan the SD card by these software and restore the images and video files from it.